can't change the C3088 pixelclock

Hi,
I'm using the C3088 cam (OV6620) together with a AVR ATmega16
microcontroller. I can read and write to the cam's registers except
for register 0x11, the Clock Rate Control register. I want to change
that register in order to change the pixel clock rate.
If I write to the register, and perform a read operation on it
immediately after the write operation, I can see that the register has
been updated. But if I perform a read operation again after a small
delay, the value of the register is reset to the default value again.

Has anyone else experienced this before?

/Peter